Seizures with a focal onset, such as temporal lobe epilepsy (TLE), are a set of debilitating disorders that affect millions of people worldwide. Despite the size of this problem, medical treatment of TLE fails in most cases. For over 40 years, the only option left for these patients has been surgery to remove the temporal lobe. Therefore, the development of novel treatments that can prevent focal seizures will have a significant impact on the quality of life of many epilepsy patients. The hypothesis guiding this R21 grant is that silencing hyperactive neurons in the Entorhinal Cortex (EC) will prevent seizures. Substantial evidence in both animal models and human patients incriminate the role of EC neurons in TLE seizures. Preliminary data show that in rodent models of TLE, EC neurons have increased firing due to increased after-depolarizing currents and increased expression of Na channel subunits. The hypothesis is that knocking down the expression of the Na channel beta-4 subunit using short-hairpinned RNA (shRNA) will reduce seizures. Recombinant adeno-associated virus (rAAV) has emerged as the top choice for human gene therapy. An important safety feature is the ability to regulate gene therapy. This will be accomplished using a newly developed tetracycline regulator cassette that controls expression of the shRNA and requires drug for activation (doxycycline-ON). The overall goal is to develop a delivery system for the shRNA that can be used in the clinic and to test its efficacy in animal models of TLE.